Methods and system of pooling storage devices

ABSTRACT

A system and method are provided for pooling storage devices in a virtual library for performing a storage operation. A storage management device determines a storage characteristic of a plurality of storage devices with respect to performing a storage operation. Based on a storage characteristic relating to performing the storage operation, the storage management device associates at least two storage devices in a virtual library. The storage management device may continuously monitor the virtual library and detect a change in storage characteristics of the storage devices. When changes in storage characteristics are detected, the storage management device may change associations of the storage device in the virtual library.

PRIORITY APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/896,563, filed Oct. 1, 2010 titled METHODS AND SYSTEM OF POOLINGSTORAGE DEVICES, which is a continuation of U.S. patent application Ser.No. 11/269,514, filed Nov. 7, 2005, which claims the benefit of U.S.provisional application No. 60/626,076 titled SYSTEM AND METHOD FORPERFORMING STORAGE OPERATIONS IN A COMPUTER NETWORK, filed Nov. 8, 2004,and U.S. provisional application No. 60/625,746 titled STORAGEMANAGEMENT SYSTEM filed Nov. 5, 2004, each of which is incorporatedherein by reference in its entirety.

OTHER RELATED APPLICATIONS

This application is related to the following pending applications, eachof which is hereby incorporated herein by reference in its entirety:

application Ser. No. 09/610,738, titled Modular Backup And RetrievalSystem Used In Conjunction With A Storage Area Network, filed Jul. 6,2000, now U.S. Pat. No. 7,035,880, issued Apr. 25, 2006;

application Ser. No. 10/658,095, titled Dynamic Storage Device PoolingIn A Computer System, filed Sep. 9, 2003, now U.S. Pat. No. 7,130,970,issued Oct. 31, 2006;

***application Ser. No. 10/819,102, titled Method And System ForControlling A Robotic Arm In A Storage Device, filed Apr. 5, 2004,attorney docket number 4982/33;

application Ser. No. 10/818,749, titled System And Method ForDynamically Performing Storage Operations In A Computer Network, filedApr. 5, 2004, now U.S. Pat. No. 7,246,207, issued Jul. 17, 2007;

application Ser. No. 10/877,831, titled Hierarchical System And MethodFor Performing Storage Operations In A Computer Network, filed Jun. 25,2004, now U.S. Pat. No. 7,454,569, issued Nov. 18, 2008;

Application Ser. No. 60/567,178, titled Hierarchical System And MethodFor Performing Storage Operations In A Computer Network, filed Apr. 30,2004;

application Ser. No. 11/120,619, titled Hierarchical Systems And MethodsFor Providing A Unified View Of Storage Information, filed May 2, 2005,attorney docket number 4982/54 now U.S. Pat. No. 7,343,453, issued Mar.11, 2008;

application Ser. No. 11/269,520, titled System And Method For PerformingMultistream Storage Operations, filed Nov. 7, 2005, now U.S. Pat. No.7,975,061, issued Jul. 5, 2011;

application Ser. No. 11/269,512, titled System And Method To SupportSingle Instance Storage Operations, filed Nov. 7, 2005 and published asU.S. Publication No. 2006/0224846 A1 on Oct. 5, 2006;

application Ser. No. 11/269,521, titled Method And System ForSelectively Deleting Stored Data, filed Nov. 7, 2005, now U.S. Pat. No.7,765,369, issued Jul. 27, 2010;

application Ser. No. 11/269,519, titled Method And System For GroupingStorage System Components, filed Nov. 7, 2005, now U.S. Pat. No.7,500,053, issued Mar. 3, 2009.

application Ser. No. 11/269,515, titled Systems And Methods ForRecovering Electronic Information From A Storage Medium, filed Nov. 7,2005, now U.S. Pat. No. 7,472,238, issued Dec. 30, 2008; and

application Ser. No. 11/269,513, titled Method And System For MonitoringA Storage Network, filed Nov. 7, 2005.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosures, as it appears in the Patent and TrademarkOffice patent files or records, but otherwise reserves all copyrightrights whatsoever.

BACKGROUND OF THE INVENTION Field of the Invention

The invention disclosed herein relates generally to data storage systemsin computer networks and, more particularly, to improvements to storagemanagement systems that allocate use of storage devices for performingstorage operations.

There are many different computing architectures for storing electronicdata. Individual computers typically store electronic data in volatilestorage devices such as Random Access Memory (RAM) and one or morenonvolatile storage devices such as hard drives, tape drives, or opticaldisks, that form a part of or are directly connectable to the individualcomputer. In a network of computers such as a Local Area Network (LAN)or a Wide Area Network (WAN), storage of electronic data is typicallyaccomplished via servers or storage devices accessible via the network.A storage device may be, for example, any device capable of storing andretrieving electronic data in a computer network, for example, a storagedevice in a computing device, such as a general-purpose computingdevice, a server, a legacy server, production server, a storage deviceused to perform a local storage operation, a storage library, tapedrives, optical libraries, Redundant Arrays of Inexpensive Disks (RAID),CD-ROM jukeboxes, or other storage devices. Such storage devices may beused to perform a storage operation using removable media, such astapes, disks, or other media. Removable media is widely utilized inperforming storage operations in storage devices. In general, only onemedia item may be placed in a storage device storage drive for use in astorage operation. If a storage device has only one storage drive, anystorage operations performed in the storage drive may cause the storagedevice to be unavailable for other uses. In addition, if the storagedevice has only one storage drive, and more than one media item may berequired to perform a storage operation, a second media item may be usedto replace a first media item in the storage drive. In this scenario,without a robotic arm or a person to manually swap tapes between drives,the storage operation could not be performed once the first media itemhas been utilized. This may cause inefficiencies in running commonstorage operations.

SUMMARY OF THE INVENTION

The present invention disclosed herein provides a method and system forcreating a virtual library that may be used to perform storageoperations.

In one embodiment of the invention, a method is provided for creating avirtual library of at least two storage devices by selecting a firststorage device and a second storage device and associating the first andsecond storage devices in a virtual library. The storage devices may bestorage devices such as a tape drive, optical drive or a hard drive. Thefirst and second storage devices may be selected in accordance with astorage characteristic, such as storage device availability, networkpathway between system components, media capacity, user preference,storage policy, or other characteristic as further described herein. Thefirst and second storage devices satisfying the storage characteristicmay be detected by a media management component, which may alsodetermine the characteristic of the storage device and logicallyassociate the first and second storage device in the virtual library.The media management component may include an index which can be used tostore data indicating a logical association of the virtual library. Thevirtual library may be maintained by detecting a third storage devicethat satisfies the storage characteristic and substituting the thirdstorage device for the first (or second) storage device bydisassociating the first (or second) storage device with the virtuallibrary and associating the third storage device with the virtuallibrary.

In another embodiment, a method is provided for performing a storageoperation using a virtual library of at least two storage devices byreceiving a request to perform a storage operation, associating a firstand second storage device in a virtual library and performing thestorage operation to the virtual library. In one embodiment, the firstand second storage device are determined to have a storagecharacteristic appropriate for the storage operation.

In another embodiment, a method for updating a virtual library of atleast two storage devices may be provided by receiving a first value ofa storage characteristic of a first storage device in the virtuallibrary and detecting a change in the storage characteristic of thefirst storage device. A third storage device may be detected that has astorage characteristic similar to the first value and the third storagedevice may be substituted with the first storage device in the virtuallibrary by disassociating the first storage device with the virtuallibrary and associating the third storage device with the virtuallibrary. Data indicating the association of a storage device with thevirtual library may be stored in an index.

In another embodiment, a method for managing a plurality of storagedevices is provided by receiving a request to perform a storageoperation and a storage characteristic (related to performing thestorage operation) of a storage device. A media management component maydetect at least two storage devices, among a plurality of storagedevices, that include the storage characteristic. The at least twostorage devices are associated with a virtual library for performingstorage operations. Data indicating the association of the storagedevices with the virtual library may be stored in an index.

In another embodiment, a method for pooling at least two storage devicesis provided in which at least two storage devices may be identified thathave a common storage characteristic. The common storage characteristicmay be related to performing a storage operation. The at least twostorage devices may be associated with a virtual library. Dataindicating the association of the storage devices with the virtuallibrary may be stored in an index.

In another embodiment, a method for storing data using a virtual libraryis provided in which a request to perform a data storage operation isreceived and a virtual library is selected which has at least twoassociated storage devices that are capable of performing the datastorage operation. The data storage operation is performed using thevirtual library.

In another embodiment, a virtual library for performing a storageoperation is provided which includes at least two storage devices. Theat least two storage devices have a storage characteristic forperforming a storage operation. A media management component iscommunicatively coupled to the at least two storage devices, and alsocommunicatively coupled to a storage manager and an index. The mediamanagement component is programmed to coordinate performing the storageoperation in the virtual library. The index includes data that indicatesan association of the at least two devices with the virtual library.

In another embodiment, a method for maintaining an index for a virtuallibrary is provided in which identifiers for two or more storage devicescapable of performing a data storage operation and satisfying at leastone common storage characteristic are stored in the index. Associationdata establishing a logical relationship of the two or more storagedevices in the virtual library may also be stored in the index. Theassociation data may be modified in response to a change in the commonstorage characteristic of a given one of the storage devices bydisassociating the given one storage device from the virtual library andassociating a third storage device satisfying the common storagecharacteristic with the virtual library.

In another embodiment, a system for performing a storage operation usingat least two storage devices is provided in which one or more storagedevices in a first computing device and one or more storage devices in asecond computing device are associated with a virtual library. Each ofthe first and second computing devices comprises a processor which maybe used to process a storage operation. The system also includes anindex for storing data indicating an association of the first and secondcomputing devices with a virtual library.

In another embodiment, a method for performing a storage operation in acomputer network is provided in which a storage manager or other systemcomponent may identify a request to perform a storage operation, forexample, based on a storage policy. The storage manager (or other systemcomponent, such as a virtual library controller) may select, in responseto a selection criteria associated with performing the storageoperation, a first computing device having a central processing unit andone or more removable media storage devices. The selection criteria maybe related to one or more storage characteristics relating to performingthe storage operation. The storage manager (or other system component,such as a virtual library controller) may select, in response to theselection criteria associated with performing the storage operation, asecond computing device having a central processing unit and one or moreremovable media storage devices. One or more index entries may becreated which associate the one or more storage devices of the firstcomputing device and the one or more storage devices of the secondcomputing device with a single logical network pathway to a networkstorage device in the computer network. The storage operation may beperformed using the single logical network pathway.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated in the figures of the accompanying drawingswhich are meant to be exemplary and not limiting, in which likereferences are intended to refer to like or corresponding parts, and inwhich:

FIG. 1 is a block diagram showing a high-level view of the networkarchitecture and components of one possible embodiment of the invention;

FIG. 1A is a block diagram showing an aspect of the network architectureand components of one possible embodiment of the invention;

FIG. 2 is a table depicting virtual libraries in one embodiment of theinvention;

FIG. 3 is a user interface depicting available virtual libraries in oneembodiment of the invention;

FIG. 4 is a flow diagram presenting a method of creating a virtuallibrary in one embodiment of the invention;

FIG. 5 is a flow diagram of a method for performing a storage operationin one embodiment of the invention;

FIG. 6 is a flow diagram presenting a method for monitoring a virtuallibrary in one embodiment of the present invention; and

FIG. 7 is a flow diagram presenting a method for performing a storageoperation in another embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention relates to creating a virtual library of storagedevices for performing a storage operation. A virtual library may be alogical collection of one or more storage devices. The storage devicesin a virtual library may be similar or heterogeneous, and may belogically grouped together to appear, for example, from the perspectiveof a user or system component, to be a single device. For example, twostorage devices, such as a server or other first computing device havinga tape drive and a stand-alone tape library connected to or otherwisecontrolled by a second computing device may be configured in a virtuallibrary and logically associated in an index.

Another virtual library may include two separate storage devices havingrobotic arms, and data indicating the logical association of the twostorage devices may be stored in an index. The index may indicate thatthe storage devices in a virtual library (e.g.—the tape drive in thefirst storage device and the one or more drives of the tape library ofthe second computing device) are represented by and accessed via asingle common logical network pathway, for example g:/virtual library 1.Thus, from the perspective of other components in a storage managementsystem, virtual library components have one logical network pathway andappear to be a single device. Such other storage management systemcomponents may perform storage operations using the virtual library viathe single logical network pathway.

The configuration of and devices used in a virtual library may vary. Forexample, a virtual library may include one or more storage devices inone computing device, such as a hard drive, and one or more storagedevices in another computing device, such as a server. By combining morethan one storage device in a virtual library, drives in each of thestorage devices may be used to perform storage operations, for example,by tape spanning across more than one tape drive, streaming data to morethan one drive, etc.

Embodiments of the invention are now described with reference to thedrawings. An embodiment of the system of the present invention is shownin FIG. 1. As shown, a system 35 may include client 20, a data store 30,a data agent 40, storage manager component 50, storage manager componentindex 52, ajobs agent 55, media management components 60 and 70, mediamanagement component indexes 62 and 72, and virtual library controllers75 and 85. Each component may be communicatively coupled to storagedevices 120, 130, 140, 150 and 160 via media management components 60and 70. Although FIG. 1 depicts a system having two media managementcomponents 60 and 70, the invention may include one or a plurality ofmedia management components providing communication between systemcomponents and storage devices.

Client 20 may include at least one attached data store 30. Data store 30may be any memory device or local data storage device known in the art,such as a hard drive, CD-ROM drive, tape drive, RAM, or other types ofmagnetic, optical, digital and/or analog local storage. Client 20includes at least one data agent 40, which may be a software module thatis generally responsible for performing storage operations for data ofclient 20, e.g., on data stored in data store 30 or other memorylocation. Storage operations include, but are not limited to, creation,storage, retrieval, migration, deletion, and tracking of electronic dataincluding primary or production volume data, as well as secondary volumedata, primary copies, secondary copies, auxiliary copies, snapshotcopies, backup copies, incremental copies, differential copies,synthetic copies, HSM copies, archive copies, Information LifecycleManagement (“ILM”) copies, and other types of copies and versions ofelectronic data. System 35 includes at least one, and typically aplurality of data agents 40 for each client. Each data agent 40 isintended to perform a storage operation relating to data associated witha different application. For example, client 20 may have differentindividual data agents 40 designed to handle MICROSOFT EXCHANGE data,LOTUS NOTES data, MICROSOFT WINDOWS file system data, MICROSOFT ACTIVEDIRECTORY OBJECTS data, and other types of data known in the art.

The storage manager 50 is generally a software module or applicationthat coordinates and controls system components, for example, thestorage manager 50 manages and controls storage operations performed bythe system 35. The storage manager 50 may communicate with allcomponents of the system 35 including client 20, data agent 40, mediamanagement components 60 and 70, and storage devices 120, 130, 140, 150and 160 to initiate and manage system storage operations. The storagemanager 50 may have an index 52, further described herein, for storingdata related to storage operations.

The media management components 60 and 70 are generally a softwaremodule that conducts data, as directed by the storage manager 50,between the client 20 and storage devices 120, 130, 140, 150 and 160.These storage devices 120, 130, 140, 150 and 160 can be storage devicessuch as a tape library, a hard drive, a magnetic media storage device,an optical media storage device, or other storage device. The mediamanagement components 60 and 70 are communicatively coupled with andcontrol the storage devices 120, 130, 140, 150 and 160. For example, themedia management components 60 and 70 might instruct a storage device120, 130, 140, 150 and 160 to perform a storage operation. The mediamanagement components 60 and 70 generally communicate with the storagedevice 120, 130, 140, 150 and 160 directly via a local bus such as aSCSI adaptor, or via a network pathway such as a LAN, WAN, etc.

Each media management component 60, 70 maintains an index cache 62, 72which stores index data that the system 35 generates during storageoperations as further described herein. For example, storage operationsfor MICROSOFT EXCHANGE data generate index data. Media managementcomponent index data includes, for example, logical network pathways ofvirtual libraries, information associating one or more devices of avirtual library, information regarding the location of the stored dataon a particular media, the location of the particular media, such as ina storage device in a current or previous configuration of a virtuallibrary, information regarding the content of the data stored such as,file names, sizes, creation dates, formats, application types, and otherfile-related criteria, information regarding one or more clientsassociated with the data stored, information regarding one or morestorage policies, storage criteria, or storage preferences associatedwith the data stored, compression information, retention-relatedinformation, encryption-related information, stream-related information,and other types of information. Thus, a media management component index62, 72 (or storage manager index 52) may be consulted in connection withperforming a storage operation on a particular data item to identify themedia to which the data is written, the storage device in which themedia is located, a current or previous configuration of a virtuallibrary that includes the storage device, or other information relatingto performing the storage operation. Index data thus provides the system35 with an efficient mechanism for performing storage operationsincluding locating user files for recovery operations and for managingand tracking stored data. In some embodiments, a storage manager index52 may contain the same information stored in a media managementcomponent index 62, 72, or the media management component index 62, 72information may instead be stored in a storage manager index 52.

The system 35 generally maintains two copies of the media managementcomponent index data regarding particular stored data. A first copy isgenerally stored with the data copied to a storage device 120, 130, 140,150, or 160. Thus, a tape may contain the stored data as well as indexinformation related to the stored data. In the event of a systemrestore, the index data stored with the stored data can be used torebuild a media management component index 62, 72 or other index usefulin performing storage operations. In addition, the media managementcomponent 60, 70 that controls the storage operation also generallywrites an additional copy of the index data to its index cache 62, 72.The data in the media management component index cache 62, 72 isgenerally stored on faster media, such as magnetic media, and is thusreadily available to the system 35 for use in storage operations andother activities without having to be retrieved from a storage device120, 130, 140, 150, or 160.

The storage manager 50 also maintains an index cache 52, database, orother data structure. Storage manager index data may be used toindicate, track, and associate logical relationships and associationsbetween components of the system 35, such as virtual libraries andvirtual library components, user preferences, management tasks, andother useful data. Some of this information may be stored in a mediamanagement component index 62 or other local data store according tosome embodiments. For example, the storage manager 50 might use itsindex cache 52 to track storage devices 120, 130, 140, 150, or 160,logical associations between media management components 60, 70 and thestorage devices 120, 130, 140, 150, or 160, and logical associations ofvirtual libraries 100, 110. In another example, index data may be usedto track client data including client archive files, storage policiesand sub-client with one or more pointers to an associated virtuallibrary. Some of the index data relating to the logical association ofthe virtual libraries 100, 110 may be information relating to thevirtual library and the individual storage devices associated with thevirtual library, such as the logical network pathways or addresses ofthe storage devices, current, previous and future virtual libraryconfigurations, storage characteristics of storage devices in a virtuallibrary, storage operations performed in a previous or currentconfiguration of a virtual library, or other information. The storagemanager 50 may also use its index cache 52 to track the status ofstorage operations performed (and to be performed) using a virtuallibrary, storage patterns associated with the system components such asmedia use, storage growth, network bandwidth, service level agreement(“SLA”) compliance levels, data protection levels, storage policyinformation, storage criteria associated with user preferences,retention criteria, storage operation preferences, and otherstorage-related information.

Index caches 52 and 62, 72 typically reside on its corresponding storagecomponent's hard disk or other fixed storage device. For example, thejobs agent 55 of a storage manager component 50 may retrieve storagemanager index 52 data regarding a storage policy and storage operationto be performed or scheduled for a particular client 20. The jobs agent55, either directly or via another system module, communicates with thedata agent 40 at the client 20 regarding the storage operation. Jobsagent 55 may also retrieve from the index cache 52 a storage policyassociated with the client 20 and uses information from the storagepolicy to communicate to the data agent 40 one or more media managementcomponents 60, 70 associated with performing storage operations for thatparticular client 20 as well as other information regarding the storageoperation to be performed such as retention criteria, encryptioncriteria, streaming criteria, etc. The data agent 40 then packages orotherwise manipulates the client data stored in the client data store 52in accordance with the storage policy information and/or according to auser preference, and communicates this client data to the appropriatemedia management component(s) 60, 70 for processing. The mediamanagement component(s) 60, 70 store the data according to storagepreferences associated with the storage policy including storing thegenerated index data with the stored data, as well as storing a copy ofthe generated index data in the media management component index cache62, 72.

A storage policy is generally a data structure or other informationwhich includes a set of preferences and other storage criteria forperforming a storage operation. The preferences and storage criteria mayinclude, but are not limited to: a storage location, relationshipsbetween system components, network pathway to utilize, retentionpolicies, data characteristics, compression or encryption requirements,preferred system components to utilize in a storage operation, and othercriteria relating to a storage operation. A storage policy may be storedto a storage manager index, to archive media as metadata for use inrestore operations or other storage operations, or to other locations orcomponents of the system.

In general, system 35 may include many configurations of virtuallibraries, e.g., 100 and 110, each of which may be configured, managedand controlled by a media management components 60, 70. Libraries 100and 110 depict storage devices arranged in virtual libraries. Forexample, library 100 includes each of the storage devices SD1-SDndepicted in FIG. 1, namely 120, 130, 140, 150 and 160. Library 110includes storage devices SD2, SD3 and SDn, or 130, 140 and 160,respectively. Each virtual library may be a logical grouping of physicalstorage devices in a network. A virtual library can also include systemcomponents other than a storage device, e.g., client, a server, a mediamanagement component, other storage device, or other system component. Avirtual library generally comprises a one or more storage devices thatare logically associated, pooled, or otherwise grouped in a library. Asexplained herein, storage devices included in the virtual library may beany type of storage device, such as a storage device in a computingdevice, such as a general-purpose computing device, a server, a legacyserver, production server, a storage device used to perform a localstorage operation, a storage library, tape drives, optical libraries,Redundant Arrays of Inexpensive Disks (RAID), CD-ROM jukeboxes, or otherstorage device. The storage devices grouped in the virtual library arelogically associated in an index. For example, the storage devices inthe virtual library may be assigned one logical network pathway, whichis stored in the index. Thus, a system component that consults the indexfor a storage library may obtain a single logical network pathway for avirtual library which may comprise one or more individual storagedevices. The virtual library appears from the perspective of the system,a user, or administrator to be a single library, which has, for example,multiple drives. In reality, the virtual library may include severalindividual storage devices, typically each having a different logicalnetwork pathway, and each of which may have only one storage drive. Insome embodiments, a virtual library controller 75 directs scheduling,actual (rather than virtual) data path selection, and transfer ofelectronic information between clients 20 and components of a virtuallibrary 120, 130, 140, 150 and 160. For example, while a virtual library120, 130, 140, 150 and 160 may logically appear as a single drive orstorage device to the system, a virtual library controller 75 may selectactual data paths for transfer of electronic information to and from thevarious individual storage device components of the virtual library 120,130, 140, 150 and 160.

In one example of a virtual library, a screen or other user interfacemay present a list of system components including a logical entry for avirtual library that includes drives A, B and C, each of which drive maybe located in a separate storage device, associated together in alibrary. In addition, each of drives A, B and C can also be presentedindividually. Configuring the storage devices 120, 130, 140, 150 and 160in a virtual library provides, among other advantages, the ability toperform storage operations which may exceed the capacity of one storagedevice by sharing the storage operation across more than one storagedevice, e.g., data can be streamed across several storage devices 120,130, 140, 150 and 160.

Storage manager 50 or media management components 60, 70 may configure,manage and control the virtual libraries 100, 110. Both of the storagemanager 50 and media management components 60, 70 may configure, manageand control the virtual libraries 100, 110. Each of the storage manager50 and media management components 60, 70 may configure the virtuallibraries 100, 110 as a single logical entity by associating the drivesof the virtual library by providing a single logical network pathway forthe virtual library. Each of the associated drives in the virtuallibrary may be accessed via the single logical network pathway.Association of drives or storage devices or other components in avirtual library may be achieved by creating a table, such as in index52, 62 and 72, which includes a virtual library identifier andinformation about the storage devices or components associated in thevirtual library, such as a single logical network address.

Referring to FIG. 1A, a virtual library 170, 172 may also be provided inother storage management system architectures, for example, without astorage manager or media management component. As shown, a virtuallibrary controller 75, in communication with a client, may manage client20 storage operations to a virtual library 170, 172. The virtual librarycontroller 75 may be a software module that may be a component of aclient 20, or communicatively coupled to and separate from the client20. The virtual library controller 75 generally communicates with avirtual library agent 126, 128, 136 and 138 to provide Storage operationinstructions. For example, the virtual library controller 75 may direct,manage and configure one or more virtual libraries 170, 172 bycommunicating with a virtual library agent 126, 128, 136, 138 for astorage device 120, 130 or computing device 125, 135. Each storagedevice 120, 130 or computer device 125, 135 may have its own virtuallibrary agent 126, 128, 136, 138 for logically associating components inthe virtual library and performing storage operations in the virtuallibrary. Information relating to the virtual libraries 170, 172, such asidentifiers for each of the components of a virtual library, such as SD1120, CD1 125, and SD2 130 (and respective drives) of virtual library 170and SD2 130 and CD2 135 of virtual library 172, and a logical networkpathway for the virtual library 170, 172 may be stored in VLC index 77.

One example of a table that may be stored in a database or in an indexthat includes virtual library information is depicted in FIG. 2. Asshown in table 175, Virtual Library 1180 includes storage devices 120,130, 140, 150 and 160 and Virtual Library n 190 includes storage devices130, 140 and 160. Virtual Library 1180 is shown having a logical networkpathway at F:Nirtual Lib 1. Thus, a system component communicating withor performing a storage operation to Virtual Library 1180 may use an Fdrive pathway. Virtual Library n 190 is shown having a logical networkpathway at G:Nirtual Lib n, and correspondingly, may be accessed via a Gdrive pathway. As shown, the individual components included in VirtualLibraries 180, 190 may be located at other drives as listed in areas 182and 192 of the table 175. Areas 182, 192 include index entries forlogical network pathways of components of a virtual library. The logicalnetwork pathway information for a virtual library may be obtained by avirtual library controller, storage manager, or other system componentand translated into the actual network pathways to each of the storagedevices included in the virtual library. For example, Virtual Library1180 accessed via logical network pathway F:Nirtual Lib 1 may betranslated into network pathways e:/ for storage device 120, h:/ forstorage device 130, etc. Table 175 can be updated as necessary toprovide information about virtual libraries such as current and previousconfigurations. One skilled in the art may recognize other ways to mapindex entries for virtual library configurations and logical networkpathways, which may also be used.

Referring again to FIG. 1, virtual library controller 75 or 85 of themedia management components 60, 70 may communicate directly with thestorage devices 120, 130, 140, 150 or 160 in a virtual library 100, 110.Virtual library controller 75, 85 may be a software module or componentof the media management component 60, 70 that communicates with virtuallibrary agent 128, 138, 148, 158, or 168, for example, providinginstructions relating to a storage operation. Virtual library agent 128,138, 148, 158, or 168 may be a software module or component associatedwith a storage device 120, 130, 140, 150 or 160, that may be a separatecomponent, or part of the storage device 120, 130, 140, 150 or 160, andthat works together with virtual library controller 75, 85 to commandand control a virtual library 100, 110 to facilitate storage operations.For example, when a media management component 60, 70 communicates witha virtual library 100, 110, the media management components 60, 70 maycommunicate its instructions to a virtual library agent 128, 138, 148,158, or 168 associated with storage devices 120, 130, 140, 150 or 160 ofvirtual library 100, 110, such as by sending the virtual library agent128, 138, 148, 158 and 168 streams of data related to a storageoperation. The virtual library controllers 75, 85 may also be programmedto regularly, or in accordance with a storage policy or storagepreference, monitor virtual libraries 100, 110 and storage devices 120,130, 140, 150 or 160 to determine storage characteristics of componentsassociated in a virtual library 100, 110. For example, a virtual librarycontroller 75, 85 may detect a change in the availability of a storagedevice, the capacity of media in a drive, network pathways, or otherstorage characteristic, further described herein.

Each storage device in the virtual library 100, 110 may include at leastone drive, such as the tape drives (SD1T1 and SD1T2, labeled 122 and124, respectively) shown in SD1 120. For example, a storage device maybe a server with a single drive, or a hard drive, single tape drive, atape library with or without a robotic arm, or other storage device.Each storage device may be grouped together with similar orheterogeneous components in a virtual library 100, 110. Data indicatingan association of the virtual library 100, 110 components and arespective logical network pathway is stored in an index 52, 62, or 72used to represent logical a storage location to a user or systemcomponent. The virtual library 100, 110, thus generally appears from theperspective of a user or system component to be a single storage devicesuch as a library having one or more drives. In reality, the virtuallibrary 100, 110 comprises one or more storage devices grouped in avirtual arrangement. Data relating to the associations of each virtuallibrary 100, 110 may be stored, for example, in the media managementcomponent index 62, 72, or in the storage manager index 52.

Referring to FIG. 3, there is shown an example of a graphical userinterface 200. Storage resources, such as available libraries 210 may bepresented to a user, including virtual libraries: library 1, library 2and library n, labeled 220, 230 and 260, respectively. The virtuallibraries may be made available via one or more servers. The availabledrives of each storage device, such as tape drives shown as SD1T1, SD1T2and SDnTn, 240, 250 and 270, respectively may also be presented to auser. Storage operations can be performed utilizing any of the availablelibraries 210, such as 220, 230 or 260. Alternatively, storageoperations can be performed directly to an available drive, such as 240,250 or 270.

Components of the system 35 may reside and execute on the same computer.A client component such as a data agent 40, a media management component60, 70, or a storage manager 50 coordinates and directs storageoperations as further described in application Ser. No. 09/610,738,attorney docket number 4982/8. This client component can functionindependently or together with other similar client components.

A method for creating a virtual library is described in connection withthe flow diagram of FIG. 4. The method could use, for example, thesystem architecture shown in FIG. 1, or other storage manager systemarchitecture. A user may initiate the process for creating a virtuallibrary by making a request to a storage manager. Alternatively, avirtual library may be created automatically without a user request. Forexample, a storage manager may automatically initiate creation of avirtual library in accordance with a storage policy, storage operationtemplate, a storage preference, or other selection criteria, condition,or characteristic. Thus, the storage manager (or media managementcomponent or other system component) may receive a storage policy whichindicates that a particular storage operation is to be performed at aparticular time or frequency interval and that the storage operationwill likely require a certain storage characteristic or selectioncriteria, such as media capacity, network pathway, componentavailability, network bandwidth or other network performance criteria,number of streams, media type, schedule, or other characteristic. Thestorage manager may monitor system components and resources to determinea particular configuration of storage devices, e.g., in a virtuallibrary, which satisfy the storage characteristic and may be capable ofperforming the storage operation.

Storage devices may be scanned to detect availability, step 300. Astorage manager may be programmed to scan (or direct the scanning of)system components for available storage devices periodically, upon arequest to perform a storage operation, or prior to a request to performa storage operation. The availability of storage devices may be obtainedby querying a media management component or storage manager or a virtuallibrary controller and virtual library agent. The media managementcomponent or storage manager may consult its index data or the virtuallibrary controller and virtual library agent to determine which storagedevices are available and which storage devices are not available.Alternatively, a storage manager or media management component mayperform a test read or write operation in a storage device drive todetermine media capacity, or other indication of availability of astorage device. For example, the system may write or read a smallquantity of data to or from one or more storage devices associated witha virtual library. In some instances, a storage device may beunavailable for one or more reasons, such as the storage device isoffline, is damaged, no longer contains media, a logical network pathwayis inaccessible, a media or tape is full, a storage device may be in usein another storage operation, or other reason. A threshold may bespecified having a minimum availability requirement for example, that astorage device must not be in use for another storage operation, that acertain quantity of network bandwidth be available for a storageoperation using the virtual library component, etc.

Characteristics of the available storage devices are identified, step310, by communicating information regarding the available storagedevices between the media management component and storage device, orvia system components including a virtual library controller, mediamanagement component, or virtual library agent. Characteristics of astorage device may include, for example, media capacity, networkpathway, storage capacity, streaming ability, processor capacity orspeed of a storage device, ability to run storage operations inparallel, authorization, security requirements or permissions of astorage device, present or scheduled future uses of the storage device,storage policies, schedules or preferences associated with a storagedevice or client, user preferences or other metrics or storage criteria.A characteristic relating to media capacity may be a required volume ofmedia to perform a storage operation. A characteristic relating tonetwork pathways may include pathways between a media managementcomponent, client, storage device or other storage component, andindications of bottlenecks or network congestion, which may affectperformance of a storage operation. A storage capacity characteristic ofa storage device may relate to a capacity of media or drives a storagedevice. Streaming ability is a characteristic of a storage device whichmay refer to the ability of a storage device to perform a storageoperation by streaming data using one or more data streams, e.g., acrossone or more drives to one or more media items. Characteristics relatingto processor capacity or speed of a storage device can indicate therelative speed in which a storage operation can be performed by astorage device and also a volume of data that can be handled by aprocessor or simply a certain processor speed of a computing deviceassociated with a component of a virtual library. Some storage deviceshave a characteristic which allows it to perform storage operations inparallel, for example, as further described in patent application Ser.No. 10/818,749. Characteristics relating to security, permissions andauthorization may limit or open up a storage device to perform certainsecure storage operations. Scheduling characteristics of a storageoperation, such as present or future uses of a storage device mayindicate that a storage device is available at discrete times andunavailable at other times to perform storage operations. A storagepolicy characteristic of a storage device may be that a particularstorage policy for a particular client may be set to perform storageoperation at a particular or associated storage device. Othercharacteristics of a storage device may be various preferences, metricsor storage criteria. Such storage device characteristics may be used toselect a storage device or other component for a virtual library basedon a criteria to perform storage operation which may require aparticular characteristic.

Indications of the characteristics or availability of a storage devicemay be presented to a user, step 320. A screen may be automaticallygenerated by a client GUI based on information received from a mediamanagement component index. The screen may provide a user with views ofavailable virtual libraries, storage devices, or drives and thecharacteristics of each. A storage manager and/or a media managementcomponent may also generate library profile information, which generallyincludes information about the library devices, and may includeadditional information, such as media capacity, logical or real networkpathway to the library, or other characteristic. Such a screen may besimilar to the graphical user interface depicted in FIG. 3 withindication information added in reference to each of Lib 1, Lib 2,SD1T1, SD1T2, or Lib n, numbered 220, 230, 240, 250, 260, respectively,such as a storage device characteristic, as further described herein.

Alternatively, a system component, such as a storage manager, mayconsult the indications of storage characteristics or availabilitywithout user input. For example, in place of user input, a storagemanager may have a template for creating a virtual library that setsadvantageous characteristics of a storage device, e.g. capacity,bandwidth, streaming capability, availability, future scheduled uses,including duration of future scheduled uses and network pathways forscheduled operations, and other characteristics as further describedherein. For example, in a template for performing a copy operation, acharacteristic may be set for a template that a storage device shouldhave no scheduled uses daily between 2:30 am and 3:30 am and have atleast two drives which are capable of performing a read or writeoperation on media having a particular capacity. Thus, the template mayestablish a minimum resource threshold required for a storage device tobe included in a virtual library and storage devices meeting orexceeding the threshold are indicated as available. Alternatively thetemplate sets forth that all available devices having a particularcharacteristic may be associated in a virtual library.

Based on the storage characteristics, storage devices may be selectedfor association in a virtual library, step 330. A user may selectstorage devices to associate in a virtual library. Or, alternatively, astorage manager or other virtual library controller, may select storagedevices based on a template and storage characteristics. Selectedstorage devices may be associated with a virtual library, step 340. Ingeneral, a decision to select storage devices for association may bebased on the indications of availability or characteristics. Forexample, a storage device may be selected because it has appropriatemedia capacity, less congested network pathway or other characteristic,e.g., as further described herein. Selection of a storage device to beincluded in a virtual library may cause an instruction to becommunicated to the applicable media management component to associate astorage device with a virtual library. When a storage device isassociated with a virtual library, a media management component updatesindex data relating to the storage device with a logical network pathwayfor the virtual library. The virtual library controller and virtuallibrary agent may also receive the association instruction from a mediamanagement component and store the association data. The virtual librarycontroller and virtual library agent may use the association data todirect and facilitate storage operations in an appropriate virtuallibrary.

The virtual library is created, step 350, by associating the storagedevices in the virtual library. Data relating to the association of thestorage device in a virtual library and which indicates a logicalnetwork pathway for the virtual library may be stored to a mediamanagement component index or other index in a table, such as the tabledepicted in FIG. 2. In general, when a virtual library is created, adefault storage policy may be applied to or used by the virtual library.Data relating to the default storage policy may be stored to the index.

A virtual library may be used to perform a storage operation, forexample, as described in reference with FIG. 5. A request is received toperform a storage operation, step 400. In general, the request may beinitiated by a user or automatically without user input according to astorage schedule, a storage policy, a user preference, or otherinitiator or criteria.

When a request is received by a system to perform a storage operation,components of a specified virtual library may be checked by identifyingdevices in the virtual library, and identifying media to handle in astorage operation. For example, a system component may verify whetherone or more storage devices are available in a virtual library, step410. In general, a media management component verifies whether a storagedevice may be available in a virtual library by consulting its indexdata to identify the storage devices associated in a virtual library.Availability of the storage device includes determining, for example,whether a storage device is online, whether the storage device isfunctioning or powered on, or other indicator of availability. Thestorage manager may consult its index to determine which mediamanagement component is associated with the storage device, or enabledto manage and control the storage device in performing the storageoperation, and communicates via the media management component todetermine availability of a storage device. The, media managementcomponent then checks to determine whether the storage device storagecharacteristics satisfy a criteria, step 420. Storage characteristicsinclude for example, requirements for performing a particular storageoperation, the specifications of the storage device, or othercharacteristics, as further described herein.

Determining whether the storage device satisfies a storage criteria caninclude, for example, determining a storage characteristic of thestorage device, such as checking each of the available storage devicesto determine whether there is adequate media capacity, such assufficient disk or tape space, e.g., a tape less than half written to orbetween half written to and full. If a tape is less than half full andthe media required for a storage operation is half of a tape, there isadequate media to perform the storage operation. If the tape is betweenhalf full and full and the media required for a storage operation is atleast half a tape, there is inadequate media to perform the storageoperation. Other characteristics may also be considered in this step,including characteristics further described herein: network pathwaybetween the media management component, client, storage device or otherstorage component, e.g. whether the network pathway is currentlycongested, likelihood of congestion in a future scheduled storageoperation, bandwidth necessary for a storage operation, processorcapacity and speed of the storage device, ability of the storage deviceto run storage operations in parallel with other storage devices in thenetwork, authorization or security requirements or permissions of thestorage device, present or scheduled future uses of the storage device,such as present or future storage operations scheduled which utilize thestorage device, storage policies, schedules, or preferences associatedwith the storage device or client, user preferences, other metric,storage criteria, or characteristic. These characteristics may be usedto predict availability of storage components as necessary for a storageoperation and to provide a comparison of efficiency of components orresources used in performing storage operations.

If the available storage devices do not satisfy the storage criteria,the storage operation fails, or the situation may be remedied, step 430.For example, if one or more storage devices do not satisfy the storagecriteria because there may be insufficient free or available storagemedia in the storage devices, the storage manager or media managementcomponent will communicate instructions to an administrator or systemuser, via email, pager, warning message, etc., to change the storagemedia in the storage devices. Alternatively, the media managementcomponent may query the available storage devices to determine whether apartial storage operation can be performed on the available storagedevices that do not otherwise satisfy each of the storage criteria. Forexample, a storage operation can be performed in parts so that a portionof the storage operation is allocated to a first virtual library andanother portion to a second or nth virtual library, storage device orother system component. Alternatively, a storage operation may beperformed in which one or more tapes in separate drives or separatestorage devices, are used in a tape-spanning configuration to perform astorage operation. In another example, a storage manager may predictstorage criteria requirements to perform the storage operation andidentify other storage device(s) that may perform the storage operationand dynamically allocate and associate such storage devices to thevirtual library.

If the storage manager or media management component determines thatthere are available storage devices and media which satisfy the storagecriteria, the available storage devices may be associated, or pooledwith a virtual library, step 440. The association of the storage devicewith a virtual library may be accomplished by storing data indicatingthe association of the virtual library in an index, such as dataindicating a logical network pathway of a virtual library. Even thoughthe storage devices associated in a virtual library may be physicaldevices that are separate geographically or mechanically, from a user'sand system perspective these devices are associated with a singlelogical network pathway and thus appear to be a single storage device,such as a storage library and not a collection of individual storagedevices.

Storage devices are associated in a virtual library, such as Library 1,shown in FIG. 1, which may be used to perform a storage operation, step450. Configuring the storage devices in a virtual library provides theability to perform storage operations which may exceed the capacity atone storage device by sharing the storage operation across more than oneindividual storage device and streaming data across several storagedevices. This configuration of the virtual library can be used for loadbalancing, e.g., performing storage operations using more than onstorage device, media spanning, e.g., performing storage operationsstoring electronic data across more than one piece of media or drive,and other high data volume storage operations.

A method for creating a virtual library described herein may beinitiated at the time a request for a storage operation is received, oralternatively, the method is initiated at other times, such as when astorage manager regularly checks and maintains system resources todetermine whether system components are available for storageoperations. For example, a storage manager may create one or morevirtual libraries in advance of a request for performing a storageoperation in accordance with predicting resource requirements forperforming storage operations according to storage policies, schedulesjobs, storage preferences, etc, and determining available resources toperform the storage operations. The system check can be triggered byuser preferences, storage policy, user instructions, or in accordancewith storage system readiness verification, further described inprovisional application Ser. No. 60/626,076 titled SYSTEM AND METHOD FORPERFORMING STORAGE OPERATIONS IN A COMPUTER NETWORK, filed Nov. 8, 2004.

A virtual library may be monitored, maintained and updated according tothe method depicted in FIG. 6. System components may be monitored ormaintained in accordance with a storage policy, step 500, to determinesystem health, capacity of system components, or other aspects of thesystem. For example, a storage manager, media management component,virtual library controller or other system component may monitoravailability of storage devices, virtual libraries and other systemcomponents and check storage policies and schedules to determine whetherthere are adequate system resources to perform future scheduled storagejobs. Monitoring of the system can be active and dynamic, e.g. initiatedin accordance with a monitoring schedule set according to storagepolicies, such as by full time virtual library agents performingheartbeat assessments or constant monitoring of system components, jobschedules, storage preference, storage policy, or passively initiated,e.g., by user request. Reports of system resources can be generatedbased on information obtained in monitoring and delivered to anadministrator or user by email, pager or other message.

In a virtual library monitoring operation, a storage manager, mediamanagement component, virtual library controller or other monitoringcomponent verifies storage devices and virtual libraries. For example, avirtual library controller detects whether there have been any changesin a characteristic of a storage device in a virtual library, step 510.A change in a characteristic may be detected by a media managementcomponent that communicates with a storage device, for example, via avirtual library agent or virtual library controller. In the event that acharacteristic of a storage device changes, data relating to the changein characteristic may be communicated to the virtual library agentassociated with the storage device and communicated to the virtuallibrary controller, storage manager, or media management component.Alternatively, a storage device, virtual library controller or othersystem component can report to the media management component that astorage device is unavailable according to a threshold range ofunavailability. Changes in characteristics can include, for example,scheduled storage operations, media capacity, availability, networkpathway, or other characteristics. Some changes in characteristics areimmaterial with respect to system resource requirements, e.g., a storagedevice may be scheduled for maintenance and taken offline for 30 minutesduring a time period in which no storage operations are scheduled, amedia change has occurred which increases the capacity of the media, orother change in characteristic which either improves the generalcharacteristics of the storage device, or which may not adversely impactfuture storage operations. Such changes may be considered to be above aminimum threshold requirement for a storage characteristic forperforming a storage operation. Some changes, however, may be materialto system resource requirements necessary for a particular storageoperation, such as failure of a storage device, scheduling conflicts,such as a future storage operation schedule that entirely utilizes allof the storage device media capacity or that is scheduled for the sametime, or other characteristic that worsens the general characteristicsof the storage device, or which will significantly impact a futurestorage operation. Such material changes may not satisfy or meet aminimum storage characteristic or criteria requirement threshold. Acharacteristic threshold between a material and immaterial differencemay be set forth such that storage devices having characteristicsexceeding the threshold are considered to be available and appropriatefor performing a particular storage operation. In general, a differencebetween a material and immaterial characteristic may be relative and maybe related to general requirements for storage operations, or set forthin threshold ranges for storage characteristic requirements.

A change in a characteristic may be determined to satisfy the thresholdcharacteristic, step 520. If the changed characteristic is determined tofall above a threshold the system monitor or check routine exits, step530. In the event that there may be a change in a storage devicecharacteristic that is not significant, there is generally no need toupdate the virtual library, thus the update check is completed and theexisting virtual library configuration is maintained. If a changedcharacteristic is determined to because the characteristic to fail tomeet the threshold, other storage devices are scanned to determinewhether another storage device may be available to be substituted into avirtual library for an unavailable storage device, step 540. If thechanged characteristic is significant, the virtual library generallymust be updated by changing a virtual library configuration.

Availability of an alternate storage device is detected, step 540, byconsulting a storage manager index, media management component index orother index, or by communicating with a virtual library or storagedevices. A storage manager or media management component determineswhether an alternate storage device is available based on satisfying acriteria requirement, step 550. If the storage device is not available,the update fails, step 560 or supplies an error message, such as anemail, page or other warning message to a user or system administrator.If a storage device is determined to be available, the storage manageror the media management component updates the configuration andassociation of devices with the virtual library to include the availablealternate storage device, step 570, and data relating to the update isstored to the media management index, storage manager index or otherindex.

Index data stored in the storage manager index or media managementcomponent index maintains information, including point-in-timeinformation about current, future and previous virtual libraryconfigurations, media, and component associations. Since virtual libraryconfigurations can change, in the event that a storage operation such asa data restore operation is performed after a change in a virtuallibrary configuration, the storage device in which the data to berestored is located may need be to be identified. Referring to FIG. 7which depicts a flowchart for determining a virtual library association,a storage operation request, such as a data restore request is received,step 600. Such request may be initiated by a user's input, according tostorage policies, or other initiator. Information about the datarelating to the storage operation, such as information about data to berestored, is also received, such as a data type, data identifier orother information. A storage manager index, media management componentindex or other index may be consulted to determine a virtual libraryassociated with the data requested in the storage operation request,step 610. In general, index data relating to a virtual libraryconfiguration is stored for current virtual library configurations andprevious virtual library configurations to track data locations andother information relating to virtual libraries. An indication of thevirtual library including the data with the storage operation requestmay be presented to a user, step 620. The indication may be presented ina graphical user interface, such as the screen depicted in FIG. 2. Thevirtual library indication may be presented to the user so that the usermay view information relating to the location of data to be restored,such as a previous and present virtual library configuration, however,this step is optional. In general, the system will perform the storagerequest, step 630, without input from the user with respect to thelocation of the data in a virtual library.

Systems and modules described herein may comprise software, firmware,hardware, or any combination(s) of software, firmware, or hardwaresuitable for the purposes described herein. Software and other modulesmay reside on servers, workstations, personal computers, computerizedtablets, PDAs, and other devices suitable for the purposes describedherein. Software and other modules may be accessible via local memory,via a network, via a browser or other application in an ASP context, orvia other means suitable for the purposes described herein. Datastructures described herein may comprise computer files, variables,programming arrays, programming structures, or any electronicinformation storage schemes or methods, or any combinations thereof,suitable for the purposes described herein. User interface elementsdescribed herein may comprise elements from graphical user interfaces,command line interfaces, and other interfaces suitable for the purposesdescribed herein. Screenshots presented and described herein can bedisplayed differently as known in the art to input, access, change,manipulate, modify, alter, and work with information.

While the invention has been described and illustrated in connectionwith preferred embodiments, many variations and modifications as will beevident to those skilled in this art may be made without departing fromthe spirit and scope of the invention, and the invention is thus not tobe limited to the precise details of methodology or construction setforth above as such variations and modification are intended to beincluded within the scope of the invention.

What is claimed is:
 1. A method for performing a storage operationcomprising: automatically detecting a change in the storagecharacteristics of a first virtual library, wherein the first virtuallibrary comprises at least, a first configuration with at least firstand second physical storage devices; automatically detecting with one ormore computer processors, at least a third physical storage deviceassociated with a second virtual library, wherein detection of the thirdphysical storage device is based at least in part on the change in thestorage characteristics of the first virtual library; automaticallyassociating with one or more computer processors the third physicalstorage device with the first virtual library without the need of userintervention; and storing a second configuration of the first virtuallibrary that comprises at least the first physical storage device, thesecond physical storage device and the third physical storage device. 2.The method of claim 1, further comprising storing data indicating anassociation of the first and second physical storage device with thefirst virtual library in an index.
 3. The method of claim 1, furthercomprising: detecting a fourth physical storage device among a pluralityof physical storage devices; disassociating the first physical storagedevice with the first virtual library; and associating the fourthphysical storage device with the first virtual library wherein the firstvirtual library comprises a third configuration with at least the secondphysical storage device, the third physical storage device and thefourth physical storage device.
 4. The method of claim 3 whereindisassociating the first physical storage device from the first virtuallibrary comprises updating an index with data indicating adisassociation of the first physical storage device with the firstvirtual library.
 5. The method of claim 1, further comprising: detectinga change in the characteristic of the first physical storage device,wherein the change in the characteristic of the first physical storagedevice causes the first physical storage device to not satisfy a storagecharacteristic threshold; identifying that a fourth physical storagedevice has a storage characteristic satisfying the storagecharacteristic threshold; disassociating the first physical storagedevice from the first virtual library; and associating the fourthphysical storage device with the first virtual library.
 6. The method ofclaim 5 wherein detecting a change in the characteristic of the firstphysical storage device comprises examining the first physical storagedevice based on receiving a first storage policy.
 7. The method of claim1 further comprising receiving a first request for data and a secondrequest for data stored on the first virtual library and automaticallydetermining that the first request is associated with data stored on thefirst configuration of the first virtual library and the second requestis associated with data stored on the second configuration of the firstvirtual library.
 8. The method of claim 1 wherein detection of the thirdphysical storage device is based at least in part on the likelihood ofcongestion associated with one or more future scheduled storageoperations.
 9. The method of claim 1 wherein the third physical storagedevice continues to be associated with the second virtual library.
 10. Asystem for performing a storage operation comprising: computer hardwarecomprising at least one or more computer processors configured toautomatically detect a change in storage characteristics of a firstvirtual library, wherein the first virtual library comprises a firstconfiguration with at least first and second physical storage devices;wherein the one or more computer processors are further configured toautomatically detect at least a third physical storage device associatedwith a second virtual library, wherein detection of the third physicalstorage device is based at least in part on the change in the storagecharacteristics of the first virtual library; wherein the one or morecomputer processors automatically associate the third physical storagedevice with the first virtual library without the need of userintervention; and wherein the one or more computer processors arefurther configured to store a second configuration of the first virtuallibrary that comprises at least the first physical storage device, thesecond physical storage device and the third physical storage device.11. The system of claim 10, further comprising an index that stores dataindicating an association of the first and second physical storagedevice with the first virtual library.
 12. The system of claim 10,further comprising: wherein the one or more computer processors furtherdetect a fourth physical storage device among a plurality of physicalstorage devices, the fourth physical storage device satisfying a secondstorage characteristic associated with a schedule of future storageoperations; wherein the one or more computer processors disassociate thefirst physical storage device with the first virtual library; andwherein the one or more computer processors associate the fourthphysical storage device with the first virtual library wherein the firstvirtual library comprises a third configuration with at least the secondphysical storage device, the third physical storage device and thefourth physical storage device.
 13. The system of claim 12 wherein theone or more computer processors are configured to update an index withdata indicating a disassociation of the first physical storage devicewith the first virtual library.
 14. The system of claim 10, furthercomprising: a characteristic associated with the first physical storagedevice, the first physical storage device being associated in the firstvirtual library; wherein the one or more computer processors detect achange in the characteristic of the first physical storage device,wherein the change in the characteristic of the first physical storagedevice causes the first physical storage device to not satisfy a storagecharacteristic threshold; a fourth physical storage device has a storagecharacteristic satisfying the storage characteristic threshold; andwherein the one or more computer processors disassociate the firstphysical storage device from the first virtual library, and associatethe fourth physical storage device with the first virtual library. 15.The system of claim 14 wherein a determination of the change in thecharacteristic of the first physical storage device comprises examiningthe first physical storage device based on receiving a first storagepolicy.
 16. The system of claim 10 further comprising a first requestfor data and a second request for data stored on the first virtuallibrary and wherein the one or more computer processors are furtherconfigured to automatically determine that the first request isassociated with data stored on the first configuration of the firstvirtual library and the second request is associated with data stored onthe second configuration of the first virtual library.
 17. The system ofclaim 10 wherein detection of the third physical storage device is basedat least in part on the likelihood of congestion associated with one ormore future scheduled storage operations.
 18. The system of claim 10wherein the third physical storage device continues to be associatedwith the second virtual library.